The objectives of this project are: 1) Describe and understand the interactions of bone cells, skin fibroblasts, lymphocytes and macrophages with the surfaces of Bioglasses of varying composition and surface characteristics; and 2) Establish a scientific basis for in vitro evaluation of toxicity and bondability of controlled surface active materials considered for use as implants. In eight different toxicity test systems Bioglasses in the form of solid discs, fibers, or powders exhibited no detectable toxicity but provides a surface compatible with cell adhesion and proliferation. Experiments comparing rates of rat calvarial cell (bone cells) multiplication, production of alkaline phosphatase activity and response to parathyroid hormone treatment show no difference between Bioglasses and controls. However, bone cells show stronger adhesion to Bioglasses than do control materials, whereas skin cells do not adhere more strongly to controls. The rapid formation of a biologically active calcium phosphate surface film on Bioglasses is associated with the bone bonding response of the material, the cellular and acellular adhesion, and we believe the lack of toxicity of the material. Mechanisms of cell adherance to Bioglasses are being investigated by analyzing fibronectin content of the interfacial attachment and varying the surface character of the substrates. Evidence for intercellular mineralization in vitro is being attained by use of analytical scanning transmission electron microscopy and scanning electron microscopy with energy dispersive X-ray analysis. The effects of collagen and fibronectin attachment to Bioglasses, in vitro tissue responses to pretreated surfaces, and the effects of composition on the attachment of soft tissues to Bioglasses are being determined and compared with the compositional dependence of the bone bonding behavior of the materials.